Project Summary Campylobacter rectus is a rod-shaped Gram-negative anaerobic oral bacterium that has been identified in 90% of adults with initial or established periodontitis, compared with 10% of healthy individuals and 20% of individuals with gingivitis. In addition to a clear association with periodontal disease, recent studies have highlighted the involvement of C. rectus infection in Barrett's esophoagus, oral and extraoral abcesses, inflammatory bowel disease and adverse pregnancy outcomes in humans including pre-term birth and low birth weight.Despite the frequent isolation of C. rectus from humans little is known about the molecular mechanisms of pathogenesis associated with this emerging pathogen.In order to begin an analysis of C. rectus pathogenesis, we will investigate whether invasion and invasion-related genes involved in Campylobacter jejuni pathogenesis are also responsible for C. rectus pathogenesis. In particular, we will 1) Determine if the C. rectus gene annotated as ciaB [Campylobacter invasion antigen B] is a functional homolog to C. jejuni ciaB; 2) Determine the secretion status of C. rectus ciaB and thereby establish whether a functional flagellar type III secretion system exists in C. rectus. Results gained from this small project will support future functional genomic studies of C. rectus on a larger scale to understand how C. rectus contributes to human disease.